Fluid analysis is used in a wide variety of research, manufacturing, waste disposal and other applications. Typically, the fluid is transported from one location to another in a primary fluid stream, and it is often desirable to analyze the contents of the stream. This may be done by taking a sample from the primary fluid stream at selected time intervals. However, the composition of the fluid stream may vary considerably between the sampling intervals, so that the samples may not accurately reflect the composition of the stream. Generally, periodic testing of a small fraction of the total quantity of a stream is acceptable, so the majority of the fluid may bypass the analyzer.
Along with the fluid stream, it may be necessary to supply a known fluid sample to an analyzer from time to time to ensure that the analyzer is functioning properly or to calibrate the analyzer. This is done by observing whether the analyzer correctly analyzes the known sample. If the analyzer does not correctly identify the known sample, then the analyzer must be calibrated until it is operating within desired parameters. Of course, if the known sample does not in fact contain the precise composition that it is believed to contain, the analyzer will be incorrectly tested and calibrated. Therefore, the known sample should be delivered to the user in a controlled condition. A method of ensuring this is for the known sample to be prepackaged in small containers such as vials in the controlled environment of a facility specializing in such matters.
Most analyzers are equipped with a sampling mechanism (i.e. sampler) capable of introducing fluid samples into the analyzer from a single stream. Sites with multiple streams to be analyzed would require several analyzers, incurring high costs due to the general high price of analyzers.